1. Field of the Invention
The present invention generally relates to a clutch disc with a torsional vibration damper for motor vehicle clutches, including: a hub for being non-rotational mounted on a transmission shaft; a hub disc located on a toothed portion with a range of rotation on the hub; cover sheets or cover plates on both sides of the hub disc which are non-rotationally connected to one another, one of the cover sheets supporting friction linings; energy storing devices for a load damper, the energy storing devices being disposed in apertures of the hub disc and Of the cover sheets, an idle damper with cover plates on both sides of a hub flange which is firmly connected to the hub; the non-rotational drive of the two cover plates with respect to the hub disc being accomplished by means of axially oriented tabs of at least one cover plate, and the tabs are circumferentially engaged, without clearance or play in, recesses of the hub disc; an axially-acting spring as a part of the load damper; and an entrained or dragged friction device located between one of the cover sheets and the idle damper, including a control plate with axial projections being engaged in circumferentially larger apertures of the hub flange and being circumferentially offset with respect to the tabs.
2. Background Information
German Patent No. 39 22 730 A1 discloses a clutch disc such as that discussed above, with an idle damper located both between two cover sheets located on the hub and laterally in relation to the hub disc. This idle damper has: a hub flange which is non-rotationally fastened to the hub; and cover plates on both sides, on which there are axially-oriented tabs. The tabs, by means of which the cover plates are non-rotationally engaged with one another, extend without play or clearance in the circumferential direction into apertures of the hub disc. As soon as the cover sheets, with deformation of the energy storage devices for the load damper, are moved out of position relative to the hub disc, there is at least some degree of friction between one of the cover sheets and the corresponding cover plate, the level of which is a function of the strength of a first spring which acts axially and corresponds to the load damper.
In contrast, the axial projections of the control plate in the hub flange of the idle damper are guided with clearance in the circumferential direction, so that only a relative rotation of the cover sheets, and thus of the control plate, relative to the hub flange, need take place before there is a synchronized movement between the control plate and the hub flange. During the first phase of movement of the control plate, the control plate consequently has a surface in frictional contact with the corresponding cover plate of the idle damper, but, during the second phase of movement, it is in similar contact with the corresponding cover sheet. The level of friction thereby generated is a function of the strength of a second, axially-acting spring which is located between the control plate and the corresponding cover plate.
For the idle damper, there is also a friction disc which is located between the cover sheet and the corresponding cover plate, and which penetrates the cover plate with a ring-shaped shoulder, which brings it into contact against the hub flange with a friction force which is a function of the strength of an additional spring located on the other side of the hub disc.
Since, on known clutch discs, for the idle damper and for the load damper, there are three different friction devices, each with a corresponding spring, the expense for components on such torsional vibration dampers can be relatively high. Moreover, since the above-mentioned components must usually be located axially in relation to one another to perform their function, the torsional vibration damper must often necessarily be quite wide.